College aantekeningen
Muscular System Summary [Essential of Human Anatomy and Physiology]
- Vak
- Instelling
- Boek
Muscular System Summary [Essential of Human Anatomy and Physiology]
[Meer zien]Voorbeeld 2 van de 5 pagina's
Voorbeeld 2 van de 5 pagina's
In winkelwagen
In winkelwagen
gesponsord bericht van onze partner
Gekoppeld boek
Titel boek:
Auteur(s):
- Uitgave:
- ISBN:
- Druk:
Verkoper
Volgen
rarereads
Voorbeeld van de inhoud
Actin and Myosin MyofilamentsMUSCULAR SYSTEM Troponin molecules – binding sites for Ca2+; attached at
Functions (M2RPC3) specific intervals along the actin myofilaments
1. Movement of the body.
2. Maintenance of posture. Tropomyosin filaments – cover the attachment sites on
3. Respiration the actin myofilaments; located along the grove bet. the
4. Production of body heat twisted strands of actin myofilaments
5. Communication
6. Constriction of organs and vessels Myosin heads – resemble golf club heads;
7. Contraction of the heart Ø Bind to attachment sites
Ø Bend and straighten
Characteristics of the Skeletal Muscle Ø Break down ATP
Skeletal Muscle
§ Constitutes approx. 40% of body weight Sarcomere
§ Muscles are attached to the skeletal system § Basic structural and functional unit of skeletal
§ Also called Striated Muscle; transverse bands or muscle
striations
Z disk – network of protein fibers forming an
Major Functional Characteristics of Skeletal Muscle attachment site for actin myofilaments
1. Contractility – ability to shorten with force
2. Excitability – capacity to respond to a stimulus I band – consists of actin myofilaments; spans each Z
3. Extensibility – ability to be stretched to their disk
normal resting length
4. Elasticity – ability to recoil to their original A band – darker, central region that extends the length
resting length of the myosin of myofilaments
Skeletal Muscle Structure H zone – second light zone that consists of myosin
Connective Tissue Coverings of Muscle myofilaments
Epimysium/Muscular fascia – connective tissue sheath
that surrounds a skeletal muscle M line – dark-staining bands
Muscle fasciculi – numerous visible bundles that make The arrangement of the actin and myosin filaments in
up the muscle sacromeres gives the myofibrils a banded appearance.
Perimysium – loose connective tissue that surrounds the The alternating I bands and A bands of the sacromeres
muscle fasciculi are responsible for the striations in the skeletal muscle
fibers.
Muscle fibers – several muscle cells that composes a
fasciculus Excitability of Muscle Fibers
Resting membrane potential – cell membranes have a
Endomysium – loose connective tissue that surrounds a negative charge on the inside relative to a positive
muscle fiber charge outside; occurs bcos there is an uneven
distribution of ions
Muscle Fiber Structure 1. Concentration of K+ inside the cell CM >
Sarcolemma – cell membrane of the muscle fiber outside the CM
2. Concentration of Na+ outside the CM > inside
Transverse tubules (T tubules) – tube-like invaginations the CM
w/c occur at regular intervals along the muscle fiber
Different types of Ion Channels
Sarcoplasmic reticulum – highly organized smooth E.R.; Ø Nongated/Leak channels – always open
has a relatively high concentration of Ca2+ (muscle
contraction) Ø Chemically gated channels – closed until a
chemical binds them and stimulates them to
Sarcoplasm – cytoplasm of a muscle fiber open
Myofibrils – threadlike structures composed of: Depolarization – the inside of the CM membrane comes
Ø Actin Myofilaments (thin filaments; purple) more positive than the outside of the cell; Na+ ions
Ø Myosin Myofilaments (thick filaments; green) move into cells
Sarcomere – highly ordered, repeating units of actin + Repolarization – the change back to the resting
myosin myofilaments; joined end to end to form the membrane potential; K+ ions moves out of cells
myofibril
Action Potentials – the rapid depolarization and
repolarization of the CM; results in muscle contraction
M o r a n o , M . A .
, Nerve Supply Aerobic Respiration – requires O2; breaks down glucose
Motor neurons – specialized nerve cells that stimulate to produce ATP, CO2, H2O
muscles to contract
Anaerobic respiration – doesn’t require O2; breaks
Neuromuscular junction – a branch that forms a down glucose to yield ATP and lactic acid
junction with a muscle fiber
Creatine phosphate – high-energy molecule that can be
Synapse – cell-to-cell junction bet. a nerve cell and stored in muscle fibers
another nerve cell/effector cell
Fatigue
Motor unit – a single motor neuron and all the skeletal § A state of reduced work capacity
muscle fibers it innervates
Muscular Fatigue – when muscle fibers use ATP faster
Presynaptic terminal – enlarged axon terminal than they are produced; when the effectiveness of Ca+ to
stimulate actin + myosin is reduced
Synaptic cleft – the space bet. the presynaptic terminal
and the muscle fiber membrane Physiological contracture – muscles may become
incapable of either contracting or relaxing
Postsynaptic membrane – the muscle fiber membrane
Psychological fatigue – involves the CNS; an individual
Synaptic vesicles – presynaptic terminal that contains perceives that continued muscle contraction is
small vesicles impossible
Acetylcholine (ACh) – neurotransmitter contained in Type of Muscle Contractions
the vesicles; a molecule released by a presynaptic nerve Isometric contractions – equal distance; length of the
cell that stimulates/inhibits a postsynaptic cell muscle does not change; the amount of tension increases
during the contraction process
Acetylcholinesterase – an enzyme that rapidly breaks
down the synaptic cleft bet. the neuron and the muscle Isotonic contraction – equal tension; the amount of
fiber tension produced by the muscle is constant during
contraction; length of the muscle decreases
Muscle Contraction Ø Cocentric contractions – isotonic; muscle
Sliding filament model – sliding of actin myofilaments tension increases as the muscle shortens
past myosin myofilaments during contraction Ø Eccentric contractions – isotonic; tension is
maintained in a muscle; the opposing resistance
Cross-bridges – myosin heads attach to the myosin causes the muscle to lengthen
attachment sites on the actin myofilaments
Muscle Tone
Muscle Twitch, Summation, Tetanus, Recruitment § Constant tension produced by body muscles
Muscle Twitch – contraction of a muscle fiber in over long periods of time
reponse to a stimulus § Responsible for keeping the back and legs
1. Lag/Latent Phase – time bet. the application of a straight, the head in an upright position, and the
stimulus and the beginning of contraction abdomen from bulging
2. Contraction Phase – time during which the
muscle contract Slow-Twitch and Fast-Twitch Fibers
3. Relaxation Phase – time during which the Classification of Muscle Fiber
muscle relaxes 1. Slow Twitch – contains type I myosin; contracts
slowly and resistant to fatigue respiration
Summation – the force of contraction of an individual
muscle fiber is increased by rapidly stimulating them 2.Fast Twitch
a. Type IIa – intermediate speed; more
Tetanus – convulsive tension; a sustained contraction fatigue resistant than type IIb
that occurs when the frequency of stimulus is so rapid b. Type IIb – contract 10x faster than type
that no relaxation occurs I
Ø Caused by Ca+ build up in the myofibrils Myglobin – stores oxygen temporarily
Recruitment – the no. of muscle fibers contraction is Hypertrophy – enlarging of muscle fibers
increased by the increasing no. of motor units stimulated
+ muscle contracts with more force Satellite cells – undifferentiated cells just below the
endomysium
Stimulus frequency – no. of times a motor neuron is
stimulated per second Smooth and Cardiac Muscle
Autorhythmicity – resulting periodic spontaneous
Energy Requirement for Muscle Contraction contraction of smooth muscle
M o r a n o , M . A .
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper rarereads. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €7,85. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 56326 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen